1. Field of the Invention
The invention relates to an operating and locking system for jail cell doors, including both a novel apparatus and method of operating same.
2. Summary of the Prior Art
For the past thirty years, the construction and operation of slidable type doors for jail cells has not been significantly changed. Each cell door is moved from a closed, locked position to an open position by an elongated rack element linearly movably mounted in a steel housing assembly constituting a top frame for the cell door and providing a horizontal track for rollers supporting the cell door. Such rack is driven by a pinion which in turn is rotated by a reversible AC motor. A lost motion connection is provided between the rack and the cell door. Normally, utility supplied 110 volt AC power is utilized to energize the motor.
The locking of the cell door is usually accomplished by a vertically downward shifting of a steel locking rod which extends downwardly on a central column in the door opening of the cell to engage a locking notch provided in a horizontal steel element forming the bottom portion of the cell door. The locking rod is shifted vertically from its locked to unlocked positions by a cam surface provided in depending relationship to the rack which is engagable with a radially projecting pin carried by the top end of the locking rod. When desired, a secondary locking element may be provided in the opposite side of the door adjacent the top of the door. The secondary locking element is likewise vertically shifted between locked and unlocked positions by a cam mounted in depending relationship to the rack and engagable with a pin projecting radially from the locking rod. The secondary locking rod cooperates with a notch or hole formed in the steel frame assembly which extends across the entire width of the cell and provides a housing for the roller track, the rack, the motor driven pinion and a mechanical backup unlocking mechanism to be described. The lost motion connection between the rack and the cell door permits initial movement of the rack to release the locking element and rod before an opening force is applied to the cell door.
The employment of utility supplied AC power as the driving energy for cell door locking and opening mechanisms is subject to several well known disadvantages. In the first place, penitentiaries are generally located in rural areas, and the utility service, if interrupted, generally requires a substantial period of time before service can be restored. If expensive diesel powered backup generators are provided, valuable time is wasted in starting the diesel engine and bringing the generator up to operational speed. Even more importantly, by utilizing AC electric motors to move the cell door from an open to a closed position, thermal cut-off of such motors is often produced by the cell occupants placing obstructions between the vertical edge of the cell door and the frame against which the door abuts in its closed position to prevent the door from reaching its closed position. Under such circumstances, the stalled 110 volt AC motor heats up in a fairly short time and a thermal overload switch conventionally incorporated within the housing of such motor opens. While this protect the motor from damage, it inherently involves a delay of at least a half hour for the motor to cool sufficiently to permit the thermal switch to be reset and the motor restored to an operating condition. During this time period, the cell door remains in its partially open position and, of course, can be manually moved or pried to a sufficiently open position to permit the cell occupant to exit from the cell.
To overcome these disadvantages, the prior art cell door operating mechanisms provided two forms of mechanical backup to loss of electrical power. Since it is common to control all of the cell doors in a cell block from a control room located so as to have visibility into all of the cells of a U-shaped cell block, a mechanical door release mechanism was provided comprising a complicated, extensive and expensive linkage which ran through the top portion of all of the cell door operating mechanisms of the cell block, even turning the corners of the U-shaped cell block. Such linkage was supposedly manually operable by a massive lever or a hand wheel mounted in or adjacent to the control room. Thus the total length of this mechanical lock releasing linkage could be on the order of at least 150 ft.. Since linear movement must be imparted to the entire linkage by the lever or hand wheel, the linear rods by which such linear movement is transmitted must be mounted in each cell block in precise alignment with the rods of adjacent cells so that frictional binding of the linkage rods will not occur which would prevent the entire linkage from being shifted by the force manually exertable by the control room guard.
As is well known to those skilled in the art of constructing jails, concrete walls are the preferred and most economical construction, but such walls cannot be accurately fabricated to define precise horizontally aligned, vertical planes, hence brackets secured to the concrete walls for supporting the actuating rods of the prior art mechanical release linkage were seldom aligned. This results in the tedious job of shimming out those portions of the concrete wall which vary horizontally from other portions of the same or other walls, so as to provide horizontally aligned surfaces on which to mount the supporting brackets for the mechanical linkage. This necessity for highly accurate installation of the very lengthy and complex mechanical backup linkage greatly increases the cost of installing a conventional cell door operating system.
Additionally, the mechanical backup linkage is necessarily mounted in a position above the rack provided for the motor operation of each cell door. The common release mechanism operated by the mechanical backup linkage includes a pivoted support frame for the motor driven pinion which drives the rack. Thus the motor driven pinion was first lifted from engagement with the rack. Further movement of the mechanical backup linkage engages the rack structure to move same to release the cell door locking members by the cams carried in depending relationship to the rack. All cell doors can then be manually rolled to their respective open positions.
All of this mechanism must necessarily be mounted above the rack, and the end result is that the total height of the top frame assembly is always 15 inches or more. Normal penitentiary construction involves only an 8 ft. height between the floor and the ceiling. This necessarily means that cell doors in excess of 6 ft. in height cannot be used, and it would be highly desirable if a 7 ft. cell door could be provided within the 8ft. floor to ceiling limitation of the most economical building structure.
Still another disadvantage of the continuous linkage of the mechanical backup mechanism is the fact that if it is not used very often or not lubricated, the frictional drag produced by rust or dirt in the multitude of bearing supports will prevent the manual operation of the linkage. Settling of the building will, of course, distort the alignment of the supporting bearings for the mechanical linkage rods and further effect a bindup of the mechanical backup system.
As mentioned above, in addition to the mechanical backup release mechanism for concurrently shifting all cell doors to an open position, the prior art locking mechanism of each cell door could be individually operated by the insertion of a specially designed key through an opening in a front panel covering the U-shaped channel which mounts the motor driven pinion, the rack, the cell door rollers and the mechanical backup linkage. The rotation of such key by an elongated lever handle will disengage the lifting of the motor driven pinion out of engagement with the rack, and move the rack sufficiently to release the cell door locks so that each cell door may be manually opened in the event of failure of the mechanical backup linkage.
Another major deficiency of prior art cell door locking systems is the fact that four separate designs of cell doors had to be provided by manufacturers in order to meet architect requirements for both right hand and left hand opening doors and right hand and left hand locations of the mechanical backup linkage. A symmetric door which could meet all of the requirements with a single design, was not available.
Lastly, prior art locking systems did not positively lock the cell door in an open position, thereby inviting abuse of the gear drive for the rack engaging pinion.
There is a need, therefore, for an improved cell door construction and operating system which will overcome each of the aforesaid disadvantages and which will occupy less vertical space at the top of the cell door opening, permitting the installation of 7 ft. cell doors.